A lighthouse is a tower, building, or other type of structure designed to emit light from a system of lamps and lenses and used as a navigational aid for maritime pilots at sea or on inland waterways.
Lighthouses mark dangerous coastlines, hazardous shoals, reefs, safe entries to harbors, and can also assist in aerial navigation. Once widely used, the number of operational lighthouses has declined due to the expense of maintenance and replacement by modern electronic navigational systems such as strobes.

The sky (or celestial dome) is everything that lies above the surface of the Earth, including the atmosphere and outer space. In the field of astronomy, the sky is also called the celestial sphere. This is viewed from Earth's surface as an imaginary dome where the sun, stars, planets, and the moon are seen to be traveling. The celestial sphere is conventionally divided into regions called constellations. Usually, the term sky is used informally as the point of view from the Earth's surface; however, the meaning and usage can vary. In some cases, such as in discussing the weather, the sky refers to only the lower, more dense portions of the atmosphere.
During daylight, the sky appears to be blue because air scatters blue sunlight more than it scatters red. At night, the sky appears to be a mostly dark surface or region scattered with stars. During the day, the Sun can be seen in the sky unless obscured by clouds. In the night sky (and to some extent during the day) the moon, p...

White is the color of fresh snow and milk, the color the human eye sees when it senses light which contains all the wavelengths of the visible spectrum.
As a symbol, white is the opposite of black, and often represents light in contrast with darkness. According to surveys in Europe and the United States, white is the color most often associated with innocence, perfection, the good, purity, honesty, cleanliness, the beginning, the new, neutrality, lightness, and exactitude.